#include <stdio.h>
#include <string.h>

void myshift(char *s) {
    int len = strlen(s);
    char c[len];
    for (int i = 0; i < len; i += 1) {
        c[i] = s[i];
    }
    for (int i = 0; i <= (len - 1) / 2; i++)
        s[i] = c[i * 2];
    for (int i = 0; i < (len - 1) / 2; i++)
        s[i + (len + 1) / 2] = c[i * 2 + 1];
}

int main() {
    char s[105];
    scanf("%s", s);
    myshift(s);
    printf("%s", s);
    return 0;
}